Question

Question 10 10.5 pts A charge is moving through a velocity selector and is moving at a speed which is a factor of 5.9 times larger than the speed not to be deflected. At this speed, the magnitude of the magnetic force acting on it is 46 Newtons. What is the electric force acting on the charge in Newtons? Hint: think what is true about the magnetic and electric force when the charge is not deflected and how the relationship between magnetic force and speed

Answer 1

When the charge is not deflected then magnetic field is perpendicular to velocity. The magnetic force is given by F_m = q (v times B) = qvB sin theta F_m = qvB (sin 90 degree = 1) Force due to electric field F_E = q^E For the charge particle not to be deflected F_m and F_e must equal and opposite such that the net force is zero. q v B = -qE v = Vertical-bar E/B Vertical-bar rightarrow speed not to be deflected For speed v_2 = 5.9 v F_m - q (5.9 v)B = 5.9 (q E/B B) 46 N = 5.9 (qE) F_e = 46/5.9 N = 7.796 N